If they're usermade guides then it's likely the images were ones posted to Discord. A while back Discord changed how images posted in their servers work, so any image shared to a different website will expire or "break" not long after. A lot of these guides were probably abandoned, so none of the images ever got fixed or rehosted elsewhere.
It's the guide they link from the weekly challenge link. I assume a moderator or someone along those lines made it. I'll go ahead and link it here so you can see.
Yeah, if you look at the url of the broken images you can see that they were originally posted to Discord. You'll have to ping or message the person who made the post to tell them to fix their images.